function popup(obj, visible) {
  var el = obj.getElementsByTagName('ul').item(0);
  if (el) {
    el.style.display = (visible) ? 'block' : 'none';
  }
}
function initpopup() {
  if (document.getElementsByTagName) {
    var elms = document.getElementsByTagName('dl');
    for (i = 0; i < elms.length; ++i) {
      var el = elms[i];
      if (el.className == 'popup') {
        el.innerHTML = el.innerHTML.replace(/<dt>/gi, '<dt onmouseover="popup(this, true);" onmouseout="popup(this, false);">');
        el.innerHTML = el.innerHTML.replace(/<li>/gi, '<li onmouseover="popup(this, true);" onmouseout="popup(this, false);">');
      }
    }
  }
}
addEvent(window, 'load', initpopup);